AbstractA cross‐sectional study of the non‐institutionalized population of the State of Iowa was completed in 1980. Persons were interviewed by telephone and a follow‐up dental examination was conducted in the home. Periodontal treatment needs were measured using the WHO‐621 Index of Periodontal Treatment Needs which has been modified and is now known as the Community Periodontal Index of Treatment Needs. Findings were consistent with other recent studies, which have shown a relatively high proportion of gingival bleeding and calculus. Although moderate pocket formation (3–6 mm) occurs in approximately 30% of the adult population, complex treatment needs (pockets 6 mm or greater) occurred in only 1.3% of the population. While sex did not significantly affect the distribution of periodontal needs; age, recency of visit to the dentist and income are possible risk factors for serious periodonta